Bright white light seen in daylight over Channel Islands moving on East to West courseBright white light seen travelling from east to west on a climbing trajectory. Weather conditions - Clear blue skies, no clouds, half moon clearly visable.Impossible to determine altitude or size of object due to lack of reference. Radial velocity from point of observation equalled approximately 120 degrees in 20 seconds. The object maintained a steady East to West course for 15 seconds before changing direction to a South South West course and climbing sharply. The object remained visable as a diminishing speck of light and appeared to be climbing at a very rapid rate.